Add some sanity checks to CREATE CAST ... WITHOUT FUNCTION. Disallow

composite, enum and array types, as those are surely not binary-compatible
with anything else because of the embedded OIDs.

Inspired by bug report by Oleg Serov.

diff --git a/src/backend/commands/functioncmds.c b/src/backend/commands/functioncmds.c
index f913f3b766155b717ce76a72e2574d0cc9a4a20a..a6dd2cb6db967881ad69b9213861a6ec16158610 100644 (file)
--- a/src/backend/commands/functioncmds.c
+++ b/src/backend/commands/functioncmds.c
@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *   $PostgreSQL: pgsql/src/backend/commands/functioncmds.c,v 1.108 2009/02/24 01:38:09 tgl Exp $
+ *   $PostgreSQL: pgsql/src/backend/commands/functioncmds.c,v 1.109 2009/03/04 11:53:53 heikki Exp $
  *
  * DESCRIPTION
  *   These routines take the parse tree and pick out the
@@ -1470,6 +1470,8 @@ CreateCast(CreateCastStmt *stmt)
 {
    Oid         sourcetypeid;
    Oid         targettypeid;
+   char        sourcetyptype;
+   char        targettyptype;
    Oid         funcid;
    int         nargs;
    char        castcontext;
@@ -1483,15 +1485,17 @@ CreateCast(CreateCastStmt *stmt)
 
    sourcetypeid = typenameTypeId(NULL, stmt->sourcetype, NULL);
    targettypeid = typenameTypeId(NULL, stmt->targettype, NULL);
+   sourcetyptype = get_typtype(sourcetypeid);
+   targettyptype = get_typtype(targettypeid);
 
    /* No pseudo-types allowed */
-   if (get_typtype(sourcetypeid) == TYPTYPE_PSEUDO)
+   if (sourcetyptype == TYPTYPE_PSEUDO)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("source data type %s is a pseudo-type",
                        TypeNameToString(stmt->sourcetype))));
 
-   if (get_typtype(targettypeid) == TYPTYPE_PSEUDO)
+   if (targettyptype == TYPTYPE_PSEUDO)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("target data type %s is a pseudo-type",
@@ -1615,6 +1619,33 @@ CreateCast(CreateCastStmt *stmt)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                     errmsg("source and target data types are not physically compatible")));
+
+       /*
+        * We know that composite, enum and array types are never binary-
+        * compatible with each other.  They all have OIDs embedded in them.
+        *
+        * Theoretically you could build a user-defined base type that is
+        * binary-compatible with a composite, enum, or array type.  But we
+        * disallow that too, as in practice such a cast is surely a mistake.
+        * You can always work around that by writing a cast function.
+        */
+       if (sourcetyptype == TYPTYPE_COMPOSITE ||
+           targettyptype == TYPTYPE_COMPOSITE)
+           ereport(ERROR,
+                   (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
+                    errmsg("composite data types are not binary-compatible")));
+
+       if (sourcetyptype == TYPTYPE_ENUM ||
+           targettyptype == TYPTYPE_ENUM)
+           ereport(ERROR,
+                   (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
+                    errmsg("enum data types are not binary-compatible")));
+
+       if (OidIsValid(get_element_type(sourcetypeid)) ||
+           OidIsValid(get_element_type(targettypeid)))
+           ereport(ERROR,
+                   (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
+                    errmsg("array data types are not binary-compatible")));
    }
 
    /*